The present invention relates to a new and improved construction of locking device for releasably fastening or locking desired parts or components to rotors or the like of fluid flow machines, wherein the base portions of the parts to be fastened are inserted in a form-locking or positively secured manner into at least approximately axially extending fixing slots or grooves arranged about the circumference of the rotor or the like, the aforesaid locking device employing fastening or securing elements which can be inserted into depressions provided in the rotor and extending transversely with respect to the axially extending fixing slots and into recesses provided in the base portion of the associated part which is to be fastened to the rotor.
In the context of this disclosure the term "part or component", which is intended to be fixed to a rotor or the like, is employed in its broadest sense as embracing one or more parts which are intended to be secured to a rotor of a machine, typically a fluid flow machine. Equally, the term "rotor" as used in the context of this disclosure is employed in its broader sense to encompass generally an annualr element, such as a rotor or rotatable wheel of such machine. Purely by way of example, and not limitation, the parts to be fastened to the rotor may be constituted by buckets or intermediate elements, wherein the rotor by way of example may be the wheel of a turbine.
The requirements which are generally placed upon locking devices of the aforementioned type as used for securing buckets or intermediate elements at fluid flow machines are that such locking devices can be easily handled and manipulated during the assembly and disassembly operations. Additionally, the locking devices should provide adequate safeguards against becoming damaged or any loss in their locking action during the operating of the machine.
Numerous proposals have already been advanced in the art for different constructional manifestations of such locking or fastening devices. Thus, for instance, there is known to the art securing or fixing devices wherein the fastening elements are inserted into a circumferential groove arranged approximately at the center of the parts which are to be fastened. These fastening elements are arranged at the ends of the teeth or serrations of the rotor disk between the axial slots and such fastening elements surround the base portion or foot of the parts which are to be secured in the axial direction.
Other constructions of securing or fastening devices have become part of the state-of-the-art wherein the fastening elements are likewise inserted into a circumferential groove of the rotor which is arranged at the outer ends of the rotor teeth and only extend over a part of the axial width of the bucket.
Apart from the foregoing there are also known fastening or securing devices which are inserted into the base of the axially extending or axial fixing slot and through the agency of hooks bent from wire or sheet metal, and which hooks engage at the end faces of the base portion of the part to be secured, fixedly hold such part in the axial slot against undesired displacement.
When using heat-resistant material, but also in consideration of other operational or performance data, these fastening devices, for instance when used with gas turbines, have been found to be partially ineffective or technically unsatisfactory. All of these locking or securing systems either are associated with the drawbacks that the last buckets of a row only can be fixed to the rotor with the aid of a special or non-standardized fastening element which in turn itself must be additionally secured, or each fastening element must be specially peened over or bent during the assembly operation. With this locking technique the bucket or the intermediate element or part must be necessarily fixed to the outer surface or end face of the base plate or the base or foot portion. Consequently, there can arise irregular or non-uniform loads, resulting in rupture of the fastening elements inserted between two buckets or that the locking action is no longer exactly and accurately fulfilled.